Switchable planetary transmissions are intended to provide adequate power to accessory assemblies, such as an air conditioner compressor and alternator, at engine idling speeds without causing those assemblies to race at high engine speeds, which may cause damage. This makes it possible to guarantee the operation of the vehicle electrical system even if the accessory assembly size might be reduced.
A switchable planetary transmission whose drive provides damping of the torsional vibrations stemming from the crankshaft is known from U.S. Pat. No. 6,250,276 (2001) which discloses a drive mechanism for accessory assemblies of a reciprocating internal combustion engine having a switchable planetary transmission which is positioned concentrically to the crankshaft and is driven by the latter. To prevent the noise- and wear-producing vibrations of the free end of the crankshaft from reaching the planetary transmission, a vibration isolator which functions as a cross-recess coupling is provided between the crankshaft and the planetary transmission. However, the transmission in '276 provides a vibration isolator disposed between the crankshaft and the planetary gear carrier, which adds to the complexity and size of the transmission, which in turn increases the manufacturing costs.
What is needed is a planetary transmission having a vibration isolator directly connected for torque flow between the input member and the one-way clutch. The present invention meets this need.